A boat carrying about 110 Bangladeshis and Rohingya Muslims from neighbouring Myanmar sank in the Bay of Bengal yesterday (NZ time) as they were heading to Malaysia and about half of them were missing, a Bangladeshi border force officer said.

The boat went down in rough seas off Teknaf, the country's southernmost town, on the Bay of Bengal, Lieutenant-Colonel Mohammad Jahid of the border guards force said.

"So far, 51 people have been rescued by coast guard, fishing boats and the border force's sea patrols," he told Reuters.

Jahid said search operations were proceeding for the others. No bodies had been recovered yet.

"We were heading to Malaysia for jobs but the boat suddenly went upside down and sank," survivor Jamir Hossain told Reuters.

"I floated for several hours before a fishing boat picked me up."

It was the second such accident in 10 days. A boat carrying about 130 people sank off Myanmar on October 28 and only a handful of people were rescued, Jahid said.

Another survivor of yesterday's sinking, Nazir Ahmed, said the boat was crammed with people, most of whom had no travel documents and had each paid 22,000 taka (NZ$326) for the journey to Malaysia.

"The boat was over-laden," Ahmed said.

Bangladeshis and members of Myanmar's Rohingya community, who face persecution in Buddhist-majority Myanmar, often make the perilous journey by sea to Southeast Asia in search of work.

The stream of Rohingyas trying to leave Myanmar has intensified this year because of violence between the Muslim community in western Myanmar's Rakhine state and Buddhists.

Nearly 200 people have been killed in intermittent clashes since June and tens of thousands, most of them Rohingyas, have been displaced.

Myanmar regards the estimated 800,000 Rohingyas in the country as illegal immigrants from Bangladesh and denies them citizenship.

Bangladesh has refused to grant Rohingyas refugee status since 1992 and regularly turns back people trying to slip out of Myanmar. The United Nations calls the Rohingyas "virtually friendless".